Peripheral data-storage subsystems which include direct access storage devices (DASD--disk recorders and reproducers) attach via I/O channels to one or more host processors. Programs executing in the host processor(s) access the DASD for recording and retrieving data. In many instances such programs search for data to be retrieved or updated by matching record identifications or record keys with such identifications or keys recorded in the DASD. In other words, particular records within a data set recorded on the DASD are being sought. For example, each DASD includes a volume table of contents (VTOC) which indexes the data stored on the respective DASD. Channel programs executing in the host processors can consume one-third of available channel time while doing a VTOC search for Allocate, Scratch and Open. Such searching is synchronously related to disk rotations which are measured in milliseconds. Such relatively extended search times reduces channel availability and hence degrades the rates of I/O operations related to such channels. It is desired to reduce the channel and host processor execution in such searching and other channel oriented peripheral operations. It is preferred if such channel utilization enhancement could be achieved in the peripheral subsystem.